Make it Java 9 compatible

[aadrian]

Please make it work with Java 9 too.

Thank you.

[smecsia]

As I can see, the only thing which does not work is the reflection hackery around the embed-process API.
This can be fixed by using our own implementation of ArtifactStore and DownloadConfig.
Will fix those things soon.

[aadrian]

@smecsia Thank you !